Power sequencing circuits play a key role in a number of applications which require a controlled application of power sources, such as computer systems, and the like. In an integrated circuit having interconnected circuitry that is powered by differing voltages, a power sequencing circuit might be used to control the application of power supply voltages to the various circuits in an orderly manner. In interconnected circuits that operate on differing voltages, the circuits operating at the lower voltages tend to be the more susceptible to damage. Alternatively, power sequencing circuits are advantageously designed to protect circuits by utilizing a circuit configuration that avoids the turn on of parasitic circuit elements that tend to damage integrated circuitry.
Those having skill in the art will understand the desirability of having a power sequencing circuit that controls power supply application and tends to prevent the creation of parasitic current paths. This type of device would necessarily provide power supply sequencing and integrated circuit damage protection by providing a circuit to control the application of power supply voltages in an integrated circuit and is coupled to the integrated circuit such that parasitic current paths tend to be eliminated, thus allowing an integrated circuit comprising individual circuits operating from differing voltages to be produced.